i just tried accessing the app with Safari and it came to my attention that its trying to load mp4 and mp3 files instead of the webm videos http://yfrog.com/h7x8xup then i got even more curious and found this file http://www.allisnotlo.st/static/js/VideoList.js look around line 236

this.src = src.replace(/(\.webm+)$/, (navigator.userAgent.indexOf('Chrome/') == -1 && (navigator.userAgent.indexOf('MSIE') != -1 || navigator.userAgent.indexOf('Safari/') != -1)) ? '.mp4' : '.webm');

but looks like they didn't upload any mp4 files :( sad